quant-ph digest — 2026-04-15
Scored against Yuan's research programme (Y1–Y6):
- Y1 — arXiv:2502.09704 — iterative warm-started QAOA
- Y2 — arXiv:2304.06915 — quasi-binary portfolio QAOA
- Y3 — arXiv:2410.16265 — QAOA DGMVP portfolio (QST 2026)
- Y4 — arXiv:2603.14744 — Grover + ADMM cardinality-constrained BO
- Y5 — arXiv:2510.08292 — GW speed-ups via Gibbs states + Pauli sparsity
- Y6 — arXiv:2510.11213 — PBR test on IBM Heron2
Source
arXiv listing: https://arxiv.org/list/quant-ph/new (85 new + 15 cross = 100 entries)
Coverage: all 100 entries scored. 11 relevant (score ≥ 1); 89 SKIP (score 0, omitted).
Scoring rubric
0–10 on method/scope/conclusion overlap — max wins. HIGH 8–10 · MED 5–7 · LOW 1–4 · SKIP 0.
Highly relevant (score 8–10) — 0 papers
None today.
Moderately relevant (score 5–7) — 4 papers
Dequantizing Short-Path Quantum Algorithms
- Authors: François Le Gall, Suguru Tamaki
- arXiv: 2604.12131
- Category: new submission — Quantum Physics (quant-ph); Computational Complexity (cs.CC); Data Structures and Algorithms (cs.DS)
- Score: 6/10 (MEDIUM)
- Overlaps with: Y4, Y5 — conclusion (dequantisation of quantum optimisation algorithms)
- Why it matters: Directly demonstrates that current short-path quantum algorithms for MAX-k-CSPs do not achieve super-quadratic advantage, providing classical algorithms with better-than-expected performance. Relevant to the quantum-vs-classical advantage landscape that Y4 and Y5 engage with.
The short-path quantum algorithm introduced by Hastings (Quantum 2018, 2019) is a variant of adiabatic quantum algorithms that enables an easier worst-case analysis by avoiding the need to control the spectral gap along a long adiabatic path. Dalzell, Pancotti, Campbell, and Brandão (STOC 2023) recently revisited this framework and obtained a clear analysis of the complexity of the short-path algorithm for several classes of constraint satisfaction problems (MAX-k-CSPs), leading to quantum algorithms with complexity 2^{(1-c)n/2} for some constant c>0. This suggested a super-quadratic quantum advantage over classical algorithms. In this work, we identify an explicit classical mechanism underlying a substantial part of this line of work, and show that it leads to clean dequantizations. As a consequence, we obtain classical algorithms that run in time 2^{(1-c')n}, for some constant c'>c, for the same classes of constraint satisfaction problems.
Classical and Quantum Speedups for Non-Convex Optimization via Energy Conserving Descent
- Authors: Yihang Sun, Huaijin Wang, Patrick Hayden, Jose Blanchet
- arXiv: 2604.13022
- Category: new submission — Quantum Physics (quant-ph); Machine Learning (cs.LG); Optimization and Control (math.OC); Machine Learning (stat.ML)
- Score: 6/10 (MEDIUM)
- Overlaps with: Y4 — method (quantum speedup for optimisation via Hamiltonian simulation); Y3 — conclusion (quantum advantage claims for optimisation)
- Why it matters: Establishes exponential quantum speedup over stochastic gradient descent for non-convex optimisation with tall barriers via a quantum Hamiltonian simulation approach. The quantum-vs-classical optimisation advantage framing is directly comparable to the analyses in Y3 and Y4.
The Energy Conserving Descent (ECD) algorithm was recently proposed (De Luca & Silverstein, 2022) as a global non-convex optimization method. Unlike gradient descent, appropriately configured ECD dynamics escape strict local minima and converge to a global minimum, making it appealing for machine learning optimization. We present the first analytical study of ECD, focusing on the one-dimensional setting for this first installment. We formalize a stochastic ECD dynamics (sECD) with energy-preserving noise, as well as a quantum analog of the ECD Hamiltonian (qECD), providing the foundation for a quantum algorithm through Hamiltonian simulation. For positive double-well objectives, we compute the expected hitting time from a local to the global minimum. We prove that both sECD and qECD yield exponential speedup over respective gradient descent baselines.
Ising selector machine by Kerr parametric oscillators
- Authors: Jacopo Tosca, Cristiano Ciuti, Claudio Conti, Marcello Calvanese Strinati
- arXiv: 2604.12718
- Category: new submission — Quantum Physics (quant-ph); Computational Physics (physics.comp-ph); Optics (physics.optics)
- Score: 5/10 (MEDIUM)
- Overlaps with: Y1, Y2, Y3 — scope (Ising Hamiltonian optimisation, combinatorial problems)
- Why it matters: Proposes a physical platform that can target not only the Ising ground state but also specific excited states, enabling Boltzmann sampling and spectral analysis of combinatorial landscapes — the same problem class addressed by QAOA in Y1–Y3.
Ising machines are physical platforms designed to minimize the energy of classical Ising Hamiltonians, yet accessing specific excited states remains an open challenge of both fundamental and practical relevance. In this letter we show that a network of Kerr parametric oscillators (KPOs) naturally implements an Ising selector machine. By tuning the frequency detuning between the parametric pump and the oscillator resonances, the system can be steered to converge close to the ground state, the highest-energy configuration, or targeted intermediate excited states. Beyond mean field, numerical simulations based on the truncated Wigner approximation demonstrate that noise insertion preserves the energetic structure of the landscape. The targeted state emerges with an exponentially enhanced probability over the rest of the Ising spectrum.
Zeno Blockade Enabling Photonic Quantum Optimization
- Authors: Mohammad-Ali Miri, Uchenna Chukwu, Nicholas Chancellor
- arXiv: 2604.13032
- Category: new submission — Quantum Physics (quant-ph)
- Score: 5/10 (MEDIUM)
- Overlaps with: Y1, Y4 — scope (quantum combinatorial optimisation with constraints); method (constraint enforcement in quantum optimisation)
- Why it matters: Uses Zeno effects to enforce independence constraints for maximum independent set — a constrained combinatorial optimisation approach analogous to the hard-constraint mixers in Y2 and the structured feasible-space search in Y4, but via a photonic platform with quantum annealing.
In this work we explore the potential of implementing an optical quantum optimizer using non-linear optics, specifically using sum-frequency generation and/or two photon absorption. This proposal uses Zeno effects to enforce independence constraints and then a linear protocol to find a maximum independent set in a way where the elements of the set can be weighted. Our proposal can either be viewed as an implementation of the entropy computing paradigm presented in [Nguyen et. al. Communications Physics 1, 411, 8] which uses real rather than imaginary time evolution, or as quantum annealing within a Zeno constrained subspace. We discuss how such a device could be built, and considerations such as error mitigation, particularly for photon-loss errors.
Tangential (score 1–4) — 7 papers
- 2604.13026 · score 4/10 · A complexity phase transition at the EPR Hamiltonian — Complexity classification of 2-local Hamiltonian optimisation problems (QMA/StoqMA phases); scope overlap with Y4 on hardness of constrained optimisation.
- 2604.11831 · score 3/10 · Q-LINK: Quantum Layerwise Information Residual Network via a Messenger Qubit for Barren Plateaus Mitigation — Layerwise VQA architecture for barren plateau mitigation; tangential method overlap with layerwise optimisation in Y1/Y3.
- 2604.11963 · score 3/10 · The Rotation Gap Is Not An Error: Ternary Structure in IBM Quantum Hardware — Characterises cooperative error structure on IBM Eagle r3 processors; scope overlap with Y3/Y6 on IBM superconducting hardware noise.
- 2604.12465 · score 3/10 · Demonstrating Record Fidelity for the Quantum Fourier Transform — Record QFT fidelity on IBM Heron r3 via Parity Architecture; scope overlap with Y6 on IBM Heron hardware demonstrations.
- 2604.12635 · score 3/10 · The Impact of Qubit Connectivity on Quantum Advantage in Noisy IQP Circuits — Connectivity-dependent noise thresholds for quantum advantage in noisy circuits; conclusion overlap with Y3 on noise-regime crossovers.
- 2604.11968 · score 2/10 · Can present be the average of the future? — Two-state vector formalism providing an alternative PBR theorem demonstration; tangential scope overlap with Y6 (PBR foundations).
- 2604.11900 · score 1/10 · Observation of feedback-directed quantum dynamics in large-scale quantum processors — Mid-circuit measurement feedback on IBM processors; loose method overlap with Y1 (measurement-based iteration on quantum hardware).
Summary table
| Score | arXiv ID | Short title | Overlaps | arXiv |
|---|---|---|---|---|
| 6 | 2604.12131 | Dequantizing Short-Path Quantum Algorithms | Y4, Y5 | link |
| 6 | 2604.13022 | Classical & Quantum Speedups via ECD | Y3, Y4 | link |
| 5 | 2604.12718 | Ising selector machine by KPOs | Y1, Y2, Y3 | link |
| 5 | 2604.13032 | Zeno Blockade Photonic Quantum Optimization | Y1, Y4 | link |
| 4 | 2604.13026 | Complexity phase transition at EPR Hamiltonian | Y4 | link |
| 3 | 2604.11831 | Q-LINK layerwise VQA | Y1, Y3 | link |
| 3 | 2604.11963 | Ternary Structure in IBM Eagle | Y3, Y6 | link |
| 3 | 2604.12465 | Record Fidelity QFT on IBM Heron | Y6 | link |
| 3 | 2604.12635 | Qubit Connectivity & Quantum Advantage | Y3 | link |
| 2 | 2604.11968 | Two-state vector PBR alternative | Y6 | link |
| 1 | 2604.11900 | Feedback-directed quantum dynamics | Y1 | link |